Invited Talks -- Interacting in Chaos -- The Viability of Modelling Socially Organised Activity -- Papers Presented -- Deriving Business Object Definitions from User Work Process Models -- Inference and Information Resources: A Design Case Study -- An Ontology for Task World Models -- Formal Models for Cooperative Tasks: Concepts and an Application for En-Route Air-Traffic Control -- The Role of Formal Proof in Modelling Interactive Behaviour -- Validating Semi-Formal Specifications of Interactors as Design Representations -- The Role of Informal Representations in Early Design -- Pragmatic Formal Design: A Case Study in Integrating Formal Methods into the HCl Development Cycle -- The Role of Verification in Interactive Systems Design -- Integrating Rendering Specifications into a Formalism for the Design of Interactive Systems -- Practical Dialogue Refinement -- Which Widgets? Deriving Implementations from User-Interface Specifications -- A Framework for Generating Spatial Configurations in User Interfaces -- Using Model Checking for the Automatic Validation of User Interfaces Systems -- Specification and Verification of Media Constraints using UPPAAL -- Modelling Direct Manipulation with Referent and Statecharts -- Integrating Joint Behaviour and Dialogue Description -- Working Group Discussions -- Discussion Topics for the DSV-IS'98 Working Groups -- Working Group 1 Report -- Working Group 2 Report -- Working Group 3 Report.